The magnetocrystalline anisotropy of gallium and aluminium substituted magnetite

作者: R.F. Pearson

DOI: 10.1051/JPHYSRAD:01959002002-3040900

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摘要: 2014 Values of K1, the first order anisotropy constant, have been measured by torque methods from 120 °K to 400 for seven crystals gallium or aluminium substituted magnetic. The ionic distribution in these has carefully determined other physical and chemical measurements a preliminary analysis made results decide relative importance mechanism contributing anomalous variation energy LE JOURNAL DE PHYSIQUE ET RADIUM TOME 20, FEVRIER-MARS 1959, Introduction. In recent years several mechanisms proposed explain observed energies ferrites. three principal mechanisms, dipole-dipole interaction, anisotropic exchange interaction between individual magnetic ions crystalline electric field, investigated Yosida Tachiki (1957) Wolf (1958) Ni, Co; Fe Mn-ferrites, although lack suitable experimental data on stoichiometric ferrite makes any exact comparison with theory very difficult. aim present work was study origin magnetocrystalline magnetite (Fe3O4) as this shows rather temperature. Previous workers (Bickford (1950)) reported that constant K1 is negative at 300 OK, passes through zero about 130,DK (the easy direction magnetization changEs [111] [100]) 119 oR crystallographic transition occurs, crystal symmetry reducing cubic orthorhombic owing long range ordering ferric ferrous octahedral lattice sites, e.g. Verwey Haayman (1941). Bickford shown cobalt change sign not due presence impurity one might therefore assume caused sbort Fe2+ Fe3+ temperatures above point. However Rado constants some mixed magnesium suggests .the give contributions opposite depending whether they occupy tetrahedral thus providing support field which predicts similar according (1957). paper are presented single nominale composition Ga,,Fe3’o4 (where x = .08, .14, .27, .36) AI.Fea-v04 y .10, .21). Substitutions were chosen because their tendency

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